Oscillatory output devices

ABSTRACT

A device for converting continuous rotary motion to oscillatory motion comprising an annular continuously rotatable member rotatable about a first fixed axis, an eccentric member mounted within the continuously rotatable member for rotation about a second movable axis parallel but eccentric to the first axis, and an output member rotatable about a third fixed axis parallel to the first and second axes, the eccentric and output members being interconnected for relative rotational movement about a fourth movable axis parallel to the third axis, the inter-relation of the four axes being such that continuous rotation of the continuously rotatable member produces displacement of the second axis about the first axis, resulting in oscillatory movement of the eccentric within the continuously rotatable member, which in turn produces oscillatory movement of the output member by virtue of the oscillation of the fourth axis about the third axis.

United States Patent 1191 Kirkland et al.

[451 Aug. 20, 1974 OSCILLATORY OUTPUT DEVICES [75] Inventors; John Henry Kirkland; Samuel Eric Harvey, both of Coventry, England [73] Assignee: Dunlop Limited, London, England [22] Filed: Dec. 6, 1972 [21] Appl. No.: 312,755

[30] Foreign Application Priority Data Primary Examiner-Harvey C. Hornsby Assistant ExaminerC. K. Moore Attorney, Agent, or Firm Stevens, Davis, Miller & Mosher [57] ABSTRACT A device for converting continuous rotary motion to oscillatory motion comprising an annular continuously rotatable member rotatable about a first fixed axis, an eccentric member mounted within the continuously rotatable member for rotation about a second movable axis parallel but eccentric to the first axis, and an output member rotatable about a third fixed axis parallel to the first and second axes, the eccentric and output members being interconnected for relative rotational movement about a fourth movable axis parallel to the third axis, the inter-relation of the four axes being such that continuous rotation of the continuously rotatable member produces displacement of the second axis about the first axis, resulting in oscillatory movement of the eccentric within the continuously rotatable member, which in turn produces oscillatory movement of the output member by virtue of the oscillation of the fourth axis about the third axis.

7 Claims, 8 Drawing Figures PATENTEDmszomm 3.829325 sum ear 5 SHEET 5 BF 5 FIG. 7.

OSCILLATORY OUTPUT DEVICES This invention relates to devices for converting continuous rotary motion to oscillatory motion and particularly, though not exclusively, to such devices for use on a part of a windscreen wiper drive.

According to one aspect of the present invention a device for converting continuous rotary motion to oscillatory motion comprises an annular continuously rotatable member rotatable about a first fixed axis, an eccentric member mounted within the continuously rotatable member for rotation about a second movable axis parallel but eccentric to the first axis, and an output member rotatable about a third fixed axis parallel to the first and second axes, the eccentric and output members being interconnected for relative rotational movement about a fourth movable axis parallel to the third axis, the inter-relation of the four axes being such that continuous rotation of the continuously rotatable member produces displacement of the second axis about the first axis, resulting in oscillatory movement of the eccentric within the continuously rotatable member, which in turn produces oscillatory movement of the output member by virtue of the oscillation of the fourth axis about the third axis.

According to a further aspect of the present invention a windscreen wiper drive device comprises an annular continuously rotatable member rotatable about a first fixed axis, an eccentric member mounted within the continuously rotatable member for rotation about a second movable axis parallel'but eccentric to the first axis, and an output member for connection to a windscreen wiper and rotatable about athird fixed axis parallel to the firstand second axis, the eccentric and output members being interconnected for relative rotational movement about a fourth movable axis parallel to the third axis, the inter-relation of the four axes being such that continuous rotation of the continuously rotatable member produces displacement of the second axis about the first axis, resulting in oscillatory movement of the eccentric within the continuously rotatable member, which in turn produces oscillatory movement of the output member and hence the windscreen wiper by virtue of the oscillation of the fourth axis about the third axis.

One embodiment of the present invention, as applied to a windscreen wiper drive device, will now be described by way of example with reference to FIGS. 1 to 8 of the accompanying drawings in which:-

FIG. 1 is a cross-sectional view of a windscreen wiper drive device in accordance with the present invention;

FIG. 2 is a sectional view on the line B-B of FIG. 1;

FIG. 3 is a diagrammatic representation of a device in accordance with the present invention capable of giving an approximately 130 oscillatory output;

FIGS. 4 and 5 are end and side views respectively of an eccentric member incorporating a spigot for use in the device shown in FIG. 1;

FIGS. 6 and 7 are end and side views respectively of a socket which receives the spigot shown in FIGS. 4 and 5, and

FIG. 8 is a plan view of a ferrous screen for use as part of a parking mechanism for use in the device shown in FIG. 1.

A windscreen wiper drive device in accordance with the present invention, as shown in FIG. 1, comprises a housing 1 within which an annular continuously rotatable member 2 is supported, in a bearing 3 and a low friction bush 4, for rotation about a first fixed axis W. Rotatable member 2 is driven by an external electric motor (not shown) via flexible drive 5 and worm gear 6 (see FIG. 2) whichengages gear teeth 7 disposed around the outer periphery of member 2.

An eccentric member 8 is mounted within continuously rotatable member 2 on hearing 9, member 8 being rotatable about a second movable axis X parallel but eccentric to axis W by a distance C (see FIG. 2).

Eccentric member 8 is provided with a spigot 10 arranged to engage a corresponding socket 11 formed in an output shaft 12. Output shaft 12 is mounted in housing 1 on bearing 13 for rotation about a fixed axis Y. The end 14 of shaft 12 projecting from housing 1 is arranged to be either directly or indirectly coupled to an associated windscreen wiper arm or arms.

Spigot 10 and socket 11 are arranged for relative rotation about a movable axis Z, spigot 10 being supported in socket 11 by bearing 15.

The device shown in FIGS. 1 and 2 functions as follows.

Continuously rotatable member 2 is driven by the electric motor (not shown), via flexible drive 5, worm gear 6 and gear teeth 7. The continuous rotation of member 2 about axis W causes the oscillatory motion of eccentric member 8 within member 2 due to the rotation of movable axis X about fixed axis W in a circle 16 of radius C (see FIG. 2).

Continuously rotatable member 2, eccentric member 8, spigot [0, socket 11 and output shaft 12 form a three bar crank mechanism (see FIG. 2), the three bars of the crank mechanism being of fixed lengths C, A and D1 respectively where C is the eccentricity of axis X about fixed axis W, A is the distance between movable axes Z and X and D1 is the distance between movable axis Z and fixed axis Y.

Thus, as can be seen from FIG. 2, the continuous rotation of axis X about axis W causes the oscillatory angular displacement of axis Z about axis Y through an angle dependent on the inter-relationship between axes W, X, Y and Z. The arrangement shown in FIG. 2 produces oscillatory motion of axis Z, and hence shaft 12, through an angle of approximately 32 degrees.

FIG. 3 shows an equivalent three bar crank diagram for an arrangement arranged to give approximately a oscillatory motion of shaft '12. The angle of oscillation of shaft 12 has been increased in FIG. 3 by shortening the distance of movable axis Z from fixed axis Y to dimension D2.

FIGS. 4 and 5 show side and end views respectively of the eccentric member 8 used in the 32 oscillatory motion arrangement shown in FIGS. 1 and 2. FIGS/6 and 7 show side and end views respectively of the socketed end of output shaft 12 which engages the spigot'l0 of eccentric member 8.

The windscreen wiper drive device is provided with a parking mechanism to enable the rest or park position of output shaft 12 and hence the associated windscreen wiper or wipers to be preset.

The parking mechanism comprises a permanent magnet 17 secured to the housing 1 by a screw 19 and spaced therefrom by a non-ferrous spacing piece 18.

Rotation of magnet 17 on the screw 19 is prevented by pegs 20. Magnet 17 is positioned within continuously rotatable member 2 adjacent the inner surface thereof. Continuously rotatable member 2 is made from nonferrous material and a reed switch 21 is positioned adjacent the outer surface of member 2 so that the field of magnet 17 normally maintains switch 21 closed during operation of the device.

A ferrous screen 22, shown in detail in FIG. 8, is screwed to the inner surface of member 2 so that it passes between magnet 17 and switch 21 once during each revolution of member 2 thereby interrupting the field of magnet 17 and rendering switch 21 nonconducting. Screen 22 is provided with a slot 23 through which screws 24 project, thereby enabling the circumferential position of the screen on member 2 to be adjusted.

The electrical circuit for the motor which drives the device shown in FIGS. 1 and 2 is arranged so that during operation of the device power is supplied directly to the motor via a control switch with off' and on positions. I

When the control switch is placed in the ofF position the supply of power to the motor is diverted through reed switch 21 so that the device will come to rest on the next occasion the screen interrupts the field magnet 17. Thus the circumferential position of screen 22 on member 2 controls the rest or park position of output shaft 12.

By housing eccentric member 8 and shaft 12 within the bearings of continuously rotatable member 2 the size of these bearings can be increased without adversely affecting the overall size of the drive device thus enabling higher powered electric motors to be employed with a resulting increase in the output torque of the device. This is of particular importance when the device is to be used for driving aircraft windscreen wipers where operation at high forward speeds combined with long wiper arms and blades place heavy torque demands on the drive device.

Although in the device described above the eccentric member is provided with a spigot and the output shaft with a socket, it will be understood by those skilled in the art that this arrangement may be reversed, or alternatively the output shaft and eccentric member may be interconnected in any other suitable manner for rotation about movable axis Z.

The device described above has the advantages of high output torque, compactness and low weight plus the added advantage that it is only necessary to vary the distance between Axes Y and Z in order to alter the angular oscillation of the output shaft of the device.

Having now described our invention, what we claim l. A windscreen wiper drive device comprising an annular continuously rotatable member rotatable about a first fixed axis, an eccentric member mounted within the continuously rotatable member for rotation about a second movable axis parallel but eccentric to the first axis, and an output member for connection to a windscreen wiper and rotatable about a third fixed axis parallel to the first and second axes, the eccentric and output members being interconnected for relative rotational movement about a fourth movable axis parallel to the third axis, the interrelation ofthe four axes being such that continuous rotation of the continuously rotatable member produces displacement of the second axis about the first axis, resulting in oscillatory movement of the eccentric within the continuously rotatable member, which in turn produces oscillatory movement of the output member and hence the windscreen wiper by virtue of the oscillation of the fourth axis about the third axis, and in which the continuously rotatable member is driven by an electric motor and incorporates a parking mechanism for ensuring that the associated windscreen wiper comes to rest in a preset position, the parking mechanism including a ferrous screen carried by the continuously rotatable member and arranged to interrupt the magnetic field between a magnet and a reed switch once per revolution of the rotatable member and hence render the reed switch nonconducting, the supply of power to the motor being controlled by an on/off switch, the arrangement being such that when the switch is placed in the off position power is supplied to the motor via the reed switch, so that on the next occasion the screen interrupts the magnetic field to the switch the power to the motor is cut off and the continuously rotatable member comes to rest with the screen between the magnet and the reed switch, and theoutput member, and hence the associated windscreen wiper, in a preset position.

2. A device for converting continuous rotary motion to oscillatory motion comprising: a continuously rotatable member rotatable about a first, fixed axis and being rotatable on a bearing; a circular eccentric member rotatably mounted on said bearing and rotatable within said continuously rotatable member, said eccentric member having a second, movable axis which is parallel and eccentric with respect to said first axis, said eccentric member being rotatable on said second axis; and an output member rotatable about a third, fixed axis parallel to the first and second axes, the eccentric and output members being interconnected for relative rotational movement about a fourth, movable axis parallel to the third axis, the interrelation of the four axes being such that continuous rotation of the continuously rotatable member produces displacement of the second axis about the first axis, resulting in oscillatory movement of the eccentric member within the continuously rotatable member, which in turn produces oscillatory movement of the output member by virtue of the oscillation of the fourth axis about the third axis.

3. A windscreen wiper drive device comprising: a continuously rotatable member rotatable about a first, fixed axis and being rotatable on a bearing; a circular eccentric member rotatably mounted on said bearing and rotatable within said continuously rotatable member, said eccentric member having a second, movable axis which is parallel and eccentric with respect to said first axis, said eccentric member being rotatable on said second axis; and an output member for connection to a windscreen wiper and rotatable about a third, fixed axis parallel to the first and second axes, the eccentric and output members being interconnected for relative rotational movement about a fourth, movable axis parallel to the third axis, the interrelation of the four axes being such that continuous rotation of the continuously rotatable member produces displacement of the second axis about the first axis, resulting in oscillatory movement of the eccentric member within the continuously rotatable member, which in turn produces oscillatory movement of the output member and hence the windscreen wiper by virtue of the oscillation of the fourth axis about the third axis.

6. A device as claimed in claim 2 wherein all of said four axes are within the diameter of said continuously rotatable member.

7. A windscreen wiper drive device as claimed in claim 3 wherein all of said four axes are within the diameter of said continuously rotatable member. 

1. A windscreen wiper drive device comprising an annular continuously rotatable member rotatable about a first fixed axis, an eccentric member mounted within the continuously rotatable member for rotation about a second movable axis parallel but eccentric to the first axis, and an output member for connection to a windscreen wiper and rotatable about a third fixed axis parallel to the first and second axes, the eccentric and output members being interconnected for relative rotational movement about a fourth movable axis parallel to the third axis, the interrelation of the four axes being such that continuous rotation of the continuously rotatable member produces displacement of the second axis about the first axis, resulting in oscillatory movement of the eccentric within the continuously rotatable member, which in turn produces oscillatory movement of the output member and hence the windscreen wiper by virtue of the oscillation of the fourth axis about the third axis, and in which the continuously rotatable member is driven by an electric motor and incorporates a parking mechanism for ensuring that the associated windscreen wiper comes to rest in a preset position, the parking mechanism including a ferrous screen carried by the continuously rotatable member and arrAnged to interrupt the magnetic field between a magnet and a reed switch once per revolution of the rotatable member and hence render the reed switch nonconducting, the supply of power to the motor being controlled by an on/off switch, the arrangement being such that when the switch is placed in the off position power is supplied to the motor via the reed switch, so that on the next occasion the screen interrupts the magnetic field to the switch the power to the motor is cut off and the continuously rotatable member comes to rest with the screen between the magnet and the reed switch, and the output member, and hence the associated windscreen wiper, in a preset position.
 2. A device for converting continuous rotary motion to oscillatory motion comprising: a continuously rotatable member rotatable about a first, fixed axis and being rotatable on a bearing; a circular eccentric member rotatably mounted on said bearing and rotatable within said continuously rotatable member, said eccentric member having a second, movable axis which is parallel and eccentric with respect to said first axis, said eccentric member being rotatable on said second axis; and an output member rotatable about a third, fixed axis parallel to the first and second axes, the eccentric and output members being interconnected for relative rotational movement about a fourth, movable axis parallel to the third axis, the interrelation of the four axes being such that continuous rotation of the continuously rotatable member produces displacement of the second axis about the first axis, resulting in oscillatory movement of the eccentric member within the continuously rotatable member, which in turn produces oscillatory movement of the output member by virtue of the oscillation of the fourth axis about the third axis.
 3. A windscreen wiper drive device comprising: a continuously rotatable member rotatable about a first, fixed axis and being rotatable on a bearing; a circular eccentric member rotatably mounted on said bearing and rotatable within said continuously rotatable member, said eccentric member having a second, movable axis which is parallel and eccentric with respect to said first axis, said eccentric member being rotatable on said second axis; and an output member for connection to a windscreen wiper and rotatable about a third, fixed axis parallel to the first and second axes, the eccentric and output members being interconnected for relative rotational movement about a fourth, movable axis parallel to the third axis, the interrelation of the four axes being such that continuous rotation of the continuously rotatable member produces displacement of the second axis about the first axis, resulting in oscillatory movement of the eccentric member within the continuously rotatable member, which in turn produces oscillatory movement of the output member and hence the windscreen wiper by virtue of the oscillation of the fourth axis about the third axis.
 4. A device according to claim 3 in which the eccentric member is provided with a spigot which engages a corresponding socket provided on the output member, the spigot being arranged to rotate within the socket about the fourth axis.
 5. A device according to claim 3 in which the continuously rotatable member is annular and is rotated via gear teeth provided on its outer periphery.
 6. A device as claimed in claim 2 wherein all of said four axes are within the diameter of said continuously rotatable member.
 7. A windscreen wiper drive device as claimed in claim 3 wherein all of said four axes are within the diameter of said continuously rotatable member. 